What is war like in the future? Is a laser-guided missile more ethical than the devastating trench warfare of the Somme offensive? Ever since the 1909 British silent film “The Airship Destroyer” depicted a future “when aeroplanes have been perfected to the point of being practicable engines of war,” science-fiction moviemakers have wondered, and worried, about warfare to come.

Films as diverse as “The War of the Worlds” (1953) and “Ender’s Game” (2013) have envisioned how technology might change armed conflict. Similarly, military-themed science fiction has inspired inventors to dream up more efficient ways to crush, kill, and destroy, whether the target is Godzilla, interstellar creatures, or ourselves.

“There’s been a bi-directional flow of influence between Hollywood and the military for many decades,” said Matthew Thomas Payne, a University of Alabama telecommunication and film professor, in an e-mail. “And sci-fi, in particular, has been an idea incubator for the robotics and defense industries, just as entertainment producers have profited from their relationship with military experts.”

“Edge of Tomorrow,” the latest entry in this genre, opened Friday. Directed by Doug Liman (“The Bourne Identity,” “Mr. & Mrs. Smith”) and starring Tom Cruise and Emily Blunt, it takes place in a near future where, once again, an alien race has invaded Earth. It’s up to Cruise and Blunt, members of the United Defense Force, to beat back these semi-mechanical, many-tendrilled “Mimics.” Cruise’s character, Major William Cage, is a military PR flack and combat greenhorn who’s also caught in an alien-induced time loop. If he dies in battle, which he does frequently, Cage gets to “reset” the day and thereby live to fight again.

The film’s arsenal of futuristic weaponry includes aircraft resembling tilt-rotor Osprey/Chinook helicopter hybrids, which air-drop soldiers in jacked-up battle armor, or “ExoSuits,” (above) that allow Cruise and Blunt to wield huge artillery and smash stuff with their super-fists.

That said, not all guns, spaceships, and tactics seen in “distant futures” are equally plausible. Here’s a brief overview of military sci-fi’s hits and misses, and what might be coming soon to a theater — of war — near you.

Guns and Ammo

From top, M41A pulse rifle, ZF-1 gun, and ARC gun.

Any list of top imaginary armaments has to include the M41A pulse rifle from “Aliens” (1986), which Sigourney Weaver and the 22d-century Colonial Marine Corps use to blast Xenomorphs. There’s also the absurd ZF-1 gun from “The Fifth Element” (1997), whose cartoonish features include a flamethrower; a freeze ray; a rocket, arrow, and net launcher; and a 300-round magazine.

But kinetic weapons shooting bullet projectiles are passé. “Energy weapons are the longer term future,” said John Lupher, CEO of Austin, Texas-based TrackingPoint, creator of what his company says is the first-ever precision guided firearm. His choice for best sci-fi firearm is the ARC gun from “District 9” (2009), which directs a blast of “protonic” current that super-heats organic targets. Lupher said a gun that produces “an invisible ionizing laser ray” providing “a path for high-voltage electricity to follow” is “entirely believable.” Although this technology would not likely explode the target, as the ARC does, he said it could “completely disable a human.”

Armor and Aircraft

Sometimes, Hollywood gets it right. “The most prescient films,” said Payne, depict “advanced warfighting robotics such as the cyborg exoskeletons featured in ‘Elysium’ and ‘Edge of Tomorrow.’ ” AMP Suits used in “Avatar” (2009) and the human-driven, giant robots from “Pacific Rim” (2013) also give viewers a taste of Rock-’em Sock-’em Robots power. As far as flying machines go, two aircraft stand out from “Avatar”: the Samson helicopter (right), like a Vietnam-era Huey but with two round rotors; and the C-21 “Dragon Assault Ship,” whose multiple cockpits and gun turrets were inspired by World War II Flying Fortress bombers. Also worth noting is the S.H.I.E.L.D. Helicarrier from “The Avengers” (2012). A flying aircraft carrier may not make sense, but it looks bad-ass.

Bad Battles

Just because Napoleon invaded Russia doesn’t mean future commanders don’t blunder, too. Take “Starship Troopers” (1997), which pits the Mobile Infantry against a species of giant insect-creatures (above). Soldiers make landfall on the Arachnids’ home planet and attack . . . with rifles. Why not drop Raid-filled bombs or deploy giant bug-zappers? Then again, that strategy wouldn’t show us what we paid to see: insect bodies ripped apart by gunfire.

Bad Robots

In movies like“The Terminator,” (above) an artificial intelligence entity called Skynet sends cyborgs through time and space to exterminate the human race. Closer to home, Waltham-based Boston Dynamics is making its own generation of robots for the Army, Navy, and Marine Corps. Their Atlas is most Terminator-like: a biped that can walk, with an articulated sensor head with stereo cameras and a laser range finder. Too bad it can’t say, “I’ll be back.”

Future of Warfare

Set in 2027, in an overpopulated, terror-ridden London, “Children of Men” (2006) shows us how war is less about heroics and more like guerrilla tactics. As for the inevitable humans vs. “green men from outer space” confrontation, the scenario of hostilities suggested by “Battle: Los Angeles” (2010) is actually plausible. Ships hover over LA, and silvery invaders land. By zeroing in on one Marine platoon’s civilian rescue effort in a single Santa Monica neighborhood, this “Battle” feels more gripping — and more realistic — than standard alien invasion fare.

Yet, not all wars set in the future (or long, long ago) are so grim. The version posited by “Star Wars” (1977), “The Empire Strikes Back” (1980), and “Return of the Jedi” (1983) is charmingly nostalgic. Pilots dogfight in bi-plane-like X-wing and TIE fighters. Jedi knights duke it out, each wielding a light saber
(above) what Obi-Wan called “an elegant weapon for a more civilized age.” Meanwhile, the planet-size, planet-destroying space station has a fatal design flaw, and those giant, four-legged AT-AT walkers are easily tripped by a cable. Technology fails. The Force wins.

“There is a deeper cultural fascination with making super weapons and becoming cyborg warriors,” added Payne, considering the Death Star and the fusion of humans and robotics in “RoboCop” (above) or “Pacific Rim.” “Popular culture likewise wrestles with the dark side of these advances.”

Besides, neither gleaming gadgetry nor autonomous drones of some future battlefield make the trenches any less cold-hearted or dehumanizing. “I die within five minutes of landing on that beach, along with every other soldier,” Cruise laments in his latest film.

Combat on the edge of tomorrow can look a lot like combat on any other day.

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